1. Field of the Invention
The invention relates to a method device for operating of an automatic start/stop system in a motor vehicle having an internal combustion engine, a manually operated gearbox and a pedal-operated clutch.
2. Description of the Prior Art
Micro hybrid vehicles and mild hybrid vehicles are motor vehicles with an internal combustion engine, a rather conventionally dimensioned electrical starter motor, an automatic stop/start system and a braking energy recovery system for charging a rather small starter battery. Using the automatic stop/start system the internal combustion engine can be automatically stopped, i.e. turned off, if no drive is required and can be started again if the driver demands power again. As a result, fuel consumption can be reduced.
There are two variants of the automatic stop/start system. The most common variant for motor vehicles with manually operated gearbox enables the stopping and restarting of the internal combustion engine only if the gearbox is in the neutral position (SIN; Stop In Neutral). With said variant the driver must select neutral, e.g. if he is approaching a traffic light at which he has to stop, to allow the automatic stop/start system to stop the internal combustion engine. However, not all drivers are in the habit of selecting neutral when they are approaching a red light, but they brake and would rather wait with gear engaged and clutch lever pressed down, so that the SIN automatic stop/start system cannot automatically stop the internal combustion engine. For said drivers a variant is more suitable that enables the stopping and restarting of the internal combustion engine with a gear engaged (SIG; Stop In Gear), and indeed not only when stationary but also at low vehicle speeds. SIG stops and starts are normally initiated if both the clutch pedal and also the brake pedal are depressed when in gear. SIG stops and starts may, however, only be carried out if the internal combustion engine is completely decoupled from the drive train.
DE 10 2009 012 573 A1 discloses a method for the operation of an automatic stop/start system in a motor vehicle with an internal combustion engine, a manually operated gearbox and a pedal-operated clutch, wherein the internal combustion engine is automatically stopped or restarted under predetermined conditions even with a gear engaged, wherein the conditions under which the internal combustion engine is automatically restarted include an indicator that indicates that an automatic restart of the internal combustion engine is safe and that is based on signals from a sensor that directly senses the position of a clutch piston and thus of the clutch plates and compares this with the so-called engagement point of the clutch, which has to be determined according to a complex method because the engagement point varies depending on a plurality of factors.
This and other known methods for the operation of an automatic stop/start system with a gear engaged all require a relatively complex sensing system, and moreover there are differences between the stop/start methods with the various SIN and SIG strategies, which takes some getting used to and is potentially irritating, especially for drivers using different motor vehicles with different stop/start-strategies.